The Mars Science Laboratory (MSL) mission that delivered Curiosity to the surface of the Red Planet was seen by NASA as a huge success, and with good reason. They landed a robot the size of a small SUV on an alien world with a rocket sled. To make that landing go as planned, MSL dropped 661 pounds (300 kilograms) of ballast, or dead weight. Now, NASA is offering a prize of $20,000 if you can come up with a good use for all that mass.

Putting anything into orbit is expensive, and the term “dead weight” doesn’t really do it justice. The reason for attaching additional mass to MSL was that it needed the ballast to eject in order to shift the center of mass prior to entering the Martian atmosphere. Still more ballast was cast off du...